Brake



P 1931- N. STERN I 1,825,555

BRAKE Filed Feb. 12, 1929 2 Shoots-Sheet 1 Sept. 29, 1931. STERN 1,825,555

BRAKE Filed Feb. 12, 1929 2 Sheets-Sheet 2 '11Ill/1111111111llllIl/Ill/IIII/IIWW Patented Sept. 29, 1931 UNITED STATES PATENT OFFICE NATHAN STERN, OF FRANKFORT-ON-THE-m, GERMANY, ABSIGNOB TO TEVES MASCHINEN-UND ARHAT'UBEN-I'ABBII GESELLSGEAIT MIT BESGHRANK- TIER HAITUNG, OF FBANK FOBT-ON-THE-m, GERMANY, A. CORPORATION BRAKE Application filed February 12, 1929, Serial No. 888,889, and in Germany November 2, 1927.

In hydraulic and other brakes for motor vehicles and the like the stops limiting the brake blocks have, in some cases, been made adjustable by means of screws or eccentrics to enable account to be taken of wear of said brake blocks. It is also known to incorporate automatic adjusting devices including self locking means in the brake linkage, the object being to lengthen the linkage when wear of the brake blocks has taken place. This, however, has the disadvantage that the entire braking force must be transmitted through these extensible devices which must play relative to the blocks corresponding to the play between the brake blocks and the brake drum. The two parts are connected together by locking means of any appropriate type. When wear of the brake blocks or brake drum has taken place the locking means advance, say by a tooth, so that the brake blocks are moved apart by a corresponding amount.

In one embodiment of the invention one of the parts constituting the sto is provided at its end with a screw thre with which the other part, embracing the first mentioned part in the fashion of a tube, engages by means of a corresponding internal thread. The tubular part is slotted at its end and the internal thread is provided in a thickened tube wall so that two or more checks are produced which enga e by their internal thread over the externa thread of the other part. The total length of the two part stop and therewith the distance between the two brake blocks may be alteredby rotation of the said two parts relatively to one another. In addition the screw thread acts as a locking means.

Embodiments of the invention are illustrated by way of example in the accompanymg drawings in which:

ig. 1 is a side elevation of one embodiment,

Fig. 2 a view to a larger scale of the lockmeans,

ig. 3 a view similar to Fig. 2 of a second embodiment,

Fig. 4 .is a longitudinal section showing a form of pawl and rack.

Fig. 5 an end view and Fig. 6 a longitudinal section showing screw engaging cheeks of different pitch.

Fig. 7 is an end view, and Fig. 8 a longitudinal section of a friction arrangement.

In the example illustrated in Figs. 1 and 2 the brake blocks are indicated by the reference letters a and b. They are rotatable about the .pivots c and d and are adapted to hear from the inside against the brake drum 6. The braking cylinder acting upon both blocks is referred to by f and the return spring by g.

Links 70 and l are pivoted to each brake block at h and z respectively, each pivot havmg a play corresponding to the amplitude of movement of the brake blocks during braking. The link 1 is provided with an external thread m. g

The other link In is tubular and its end is divided by several slots into a number of cheeks n which at their forward edge 0 are thickened or turned up and are provided there with ane-or two threads engaging with the external thread m.

If, due towear of the brake blocks or brake drum, the braking movement has beto the axis on one side and an acute angle on the other side Fig. 4.

In certain circumstances the external and internal threads may be designed with different pitches Figs. 5 and 6. In this case the internally threaded portions 0 of the individual cheeks n of the stop part is must be offset relatively to one another by fractions of the pitch of the external thread m so that even on relative displacement of the two parts Z and is through a fraction of the pitch of the thread of one of the cheeks n snaps with its threads 0 into the external thread 122. In this construction the threads 0' on the cheeks n are preferably extended over a slight width only.

In the construction illustrated in Fig. 3 the two brake blocks are in the same manner as above described.

The two stop parts A: and Z are pivoted with play. The part is is provided with a spring locking tooth p, while the link Z is furnished with a corresponding locking rack q, in which the tooth p engages.

Thus the two links In and l with the tooth .p and rack g respectively support one another and thus constitute a stop for the brake blocks a and b. The play at the pivots h and Z, moreover. allows of the brakes being applied without the links is and Z being influenced thereby.

If, however, the brake blocks become worn at their outer periphery or the brake drum at its inner periphery then the brake blocks on application against the drum have to move through a larger path. As a result the two links I: and Z are drawn apart so that the tooth p snaps into the next notch in the rack and thus holds the two links and Z in t e new extended position. If still further wear took place the tooth p would snap into the following notch. Thus the total length of the two links is and Z will become correspondingly larger and said two links constitute a stop for the brake blocks which is always in the correct position and the braking movement of the brake blocks need never be larger than when the brake blocks are unworn.

The pitch of the teeth may naturally be designed to meet requirements, for example so that even a comparatively small wear results in adjustment taking place. If occasion demand this tooth and rack lock arrangement may be replaced by suitable friction or clamping locking means working by means of a friction bloc a wedge, a sphere, a clamping or jamming roller or the like.

A form of a friction block device is illustrated in Figs. 7 and 8, wherein m is a smooth surface replacing the serrated surface m of the other forms illustrated, and the ends 1' of the cheeks n are not serrated so as to frictionally engage the portion m.

Similarly it is also possible to provide each link is and Z with a separate locking means which cooperates with a suitable point on the brake block support.

The stop is particularly applicable to hydraulic brakes although naturally it may also be used for any other type of brakes such as pneumatic, electrical, mechanical or the like brakes.

lVhat I claim is:

1. A brake comprising a brake drum, two brake shoes therefor and means to move the shoes into and out of engagement with the drum; in combination with a member loosely connected at one end to one of said shoes, spring fingers on the other end of the member, a second member loosely connected to the other shoe and having a screw thread thereon engaged by the fingers, said fingers differing in length by a fraction of the pitch of said thread.

2. A brake comprising a brake drum, two brake shoes therefor and means to move the shoes into and out of contact with the drum; in combination with a tube loosely connected at one end to a shoe and having spring fingers, and a second element loosely connected at one end to the other shoe and having on its opposite end a screw thread entering the tube between the fingers, said fingers engaging the thread at points differing a fraction of the pitch of the thread.

In testimony that I claim the foregoing as my invention, I have signed my name this 29th day of January, 1929.

NATHAN STERN. 

